System for assembling a disk drive using a robotic end effector

ABSTRACT

A robotic tool for assembling a portion of a disk drive includes a movable end effector that includes a first portion and a second portion that is movable relative to the first portion. The first portion may be configured to engage the actuator assembly and the second portion may be configured to engage the flex circuit connector. A controller may be provided to control the movable end effector, causing the end effector to pick up the head stack assembly in a first configuration, move the second portion of the end effector relative to the first portion thereof so as to articulate the head stack assembly into a second configuration that is different than the first configuration, and place the head stack assembly into the base.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.11/359,694, filed Feb. 22, 2006, now U.S. Pat. No. 7,490,398, which isincorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention pertains to the field of disk drives. Inparticular, embodiments of the present invention relate to methods andsystems for assembling disk drives.

2. Description of the Related Art

During assembly of a disk drive, a Head Stack Assembly (HSA) must bepicked from a HSA shipping tray and placed into a Head Disk Assembly(HDA) or an intermediate fixture. Conventionally, this pick and placeoperation is carried out by manually picking up a HSA from a HSAshipping tray and manually placing the picked up HSA into the HDA or theintermediate fixture. Even through the workers are grounded, theincidence of damage to the HSA through electrostatic discharge (ESD),although reduced, is not eliminated.

The HSA typically includes a flex circuit that electrically couples theFlex Circuit Connector (FCC) to the tail stack of the HSA. The flexcircuit may be formed of an electrically insulating material in which aplurality of electrical traces is embedded. Although the flex circuit istypically formed of relatively tough polyimide (sold by DuPont, Inc.under the trade name Capton®, for example), it remains susceptible toscratches and abrasion damage. Such scratches may occur when the tailstack of the HSA contacts the flex circuit during shipment or when theHSA is placed into the disk drive during assembly. To reduce theincidence of such scratches, head stack assemblies are typically shippedin a HSA shipping tray in a configuration in which the flex circuit isheld away from the tail stack of the HSA.

FIG. 1 shows a typical HSA shipping tray 102 in which HSAs are shipped.As shown, the HSA shipping tray 102 may be injection molded or may be arelatively inexpensive thermo-formed plastic tray that defines aplurality of recesses 104 shaped so as to receive a single HSA. Forclarity of illustration only a single HSA 106 is shown received withinone of the recesses 104. As shown, the HSA 106 may include a FCC 110 anda flex circuit 108. As shown, to avoid damaging the flex circuit 108during shipping, the recesses within the HSA shipping tray areconfigured so as to keep the FCC 110 away from the actuator arms and theactuator body of the actuator assembly of the HSA 106.

FIG. 2 is a plan view of a portion of a HSA shipping tray 102, showing aHSA 106 fitted within one of the recesses 104 therein. As shown, the FCC110 may be disposed within the HSA shipping tray 102 such that the flexcircuit 108 is disposed apart from the tail stack 202 of the HSA 106. Adistance 204 between the flex circuit 108 and tail stack 202 is chosento be sufficiently large so as to significantly reduce the incidence ofabrasion damage to the flex circuit 108—that is to prevent the tailstack 202 or other structures of the HSA 106 from coming into contactwith the flex circuit 108 during both the shipping and assemblyprocesses.

However, the HSAs, while shipped in a configuration that reduces theincidence of potentially yield-reducing abrasions to the flex circuit108, are typically coupled to the base of a disk drive in a differentconfiguration. FIG. 3 shows a head stack assembly 106 in this “coupling”configuration, enabling it to be coupled to the base 302 of a diskdrive. When coupled to the base 302, the HSA 106 is often placed in aconfiguration in which the flex circuit 108 is comparatively closer tothe actuator arms and actuator body of the actuator assembly of HSA 106than it is when the HSA 106 is disposed within the HSA shipping tray102. Solely to aid in visualizing the difference between theconfiguration of the HSA 106 when fitted within the HSA shipping tray102 and the configuration of the HSA 106 when coupled to the disk drivebase 302, the flex circuit 108 appears twice in FIG. 3. The flex circuit108 shown in dashed lines illustrates the relative position of the flexcircuit 108 when the HSA 106 is disposed within the HSA shipping tray102. In contrast, the flex circuit 108 shown in solid lines representsthe position thereof when the HSA 106 is placed within the disk drivebase 302. As may be seen from this composite view, the flex circuit 108is moved closer to the actuator arms and actuator body of the HSA 106 toplace it into the disk drive base 302.

From the foregoing, it is apparent that the FCC 110 must be somehowarticulated relative to the actuator assembly from its firstconfiguration in the HSA shipping tray 102 to a second configurationsuitable for placing it into a disk drive base 302. Manually picking upthe HSAs from the HSA shipping tray does not completely obviate the riskof scratching the flex circuit. Indeed, in some shipping trays, theconfiguration of the HSA 106 in the shipping tray 102 is such that aperson must pick up the HSA 106 by placing his or her fingertips within0.5 inches of the tail stack 202. Under such circumstances, even thesmallest human error can produce damage. What are needed, therefore, aremethods and systems for effectively assembling a portion of a diskdrive.

SUMMARY

An embodiment of the present invention is a method for assembling aportion of a disk drive using a robotic end effector. The disk driveincludes a base and a head stack assembly, the head stack assemblyincluding an actuator assembly, a flex circuit coupled to the actuatorassembly and a flex circuit connector coupled to the flex circuit. Themethod may include steps of coupling the robotic end effector to thehead stack assembly, the head stack assembly being disposed in a firstconfiguration; articulating the robotic end effector, such that the headstack assembly is placed in a second configuration that is differentthan the first configuration; aligning the robotic end effector with thebase; and placing the head stack assembly into the base.

The flex circuit connector may be closer to the actuator assembly in thesecond configuration than in the first configuration. The coupling stepmay include a step of coupling the robotic end effector to both theactuator assembly and the flex circuit connector. The actuator assemblymay include a pivot assembly, and the coupling step may include steps ofmoving first and second fingers of the robotic end effector tomechanically grip the pivot assembly of the actuator assembly; andapplying suction through the robotic end effector to the flex circuitconnector. The robotic end effector may include a first portion and asecond portion that is movable relative to the first portion. Thecoupling step may include steps of coupling the first portion of therobotic end effector to the actuator assembly; and coupling the secondportion of the robotic end effector to the flex circuit connector. Thearticulating step may include a step of moving the second portionrelative to the first portion to place the head stack assembly in thesecond configuration. The method may also include a step of merging thehead stack assembly with opposing magnets of a voice coil motor afterthe coupling step and before the placing step. The articulating step maybe carried out after the merging step.

Another embodiment of the present invention comprises a robotic tool forassembling a portion of a disk drive, the disk drive including a baseand a head stack assembly. The head stack assembly may include anactuator assembly, a flex circuit coupled to the actuator assembly and aflex circuit connector coupled to the flex circuit. According to thisembodiment, the robotic tool may include a movable end effectorincluding a first portion and a second portion that is movable relativeto the first portion, the first portion being configured to engage theactuator assembly and the second portion being configured to engage theflex circuit connector; a controller configured to control the movableend effector, the controller operable to cause the end effector to: pickup the head stack assembly in a first configuration, move the secondportion of the end effector relative to the first portion thereof so asto articulate the head stack assembly into a second configuration thatis different than the first configuration, and place the head stackassembly into the base.

The actuator assembly may include a pivot assembly, the first portionmay include fingers configured to grip the pivot assembly, and thesecond portion may be configured to apply suction to the flex circuitconnector. The robotic tool may also include an air merge nest that isconfigured to enable the head stack assembly to be merged with magnetsof a voice coil motor. The controller may be further operable to causethe movable end effector to merge the head stack assembly with themagnets of the voice coil motor in the air merge nest before the headstack assembly is placed into the base.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an exemplary HSA shipping tray in which head stackassemblies may be shipped.

FIG. 2 is a plan view of a portion of the HSA shipping tray of FIG. 1,showing a head stack assembly received within a recess defined therein.

FIG. 3 shows an exemplary head stack assembly coupled to a base of adisk drive.

FIG. 4 shows a first view of a disk drive assembly station that includesa robotic tool for assembling a portion of a disk drive, according to anembodiment of the present invention.

FIG. 5 shows a plan view of the disk drive assembly station of FIG. 4.

FIG. 6 shows a HSA coupled to an end effector of the robotic tool ofFIG. 4.

FIG. 7A shows the HSA disposed in a first configuration and coupled tothe end effector of the robotic tool of FIG. 4, according to anembodiment of the present invention.

FIG. 7B shows the HSA of FIG. 7A disposed in a second configuration thatis different than the first configuration and coupled to the endeffector of the robotic tool.

DETAILED DESCRIPTION

FIG. 4 shows a perspective view, and FIG. 5 shows a plan view of aportion of an assembly station 400 that includes a robotic tool 402 forassembling a portion of a disk drive, according to an embodiment of thepresent invention. The robotic tool 402 may be any portion of any typeof robot, and, for example, may include a Selective Compliance AssemblyRobot Arm (SCARA) robot, such as the Adept Cobra™ line of robotsavailable from Adept Technology, Inc.

As shown therein, the assembly station 400 may include a disk driveassembly conveyor 410 by which disk drive bases and/or other componentsmay be conveyed to the assembly station 400 for further processing.

The robotic assembly station 400 may further include a Voice Coil Motor(VCM) shipping tray receiving portion 406 and a HSA shipping trayreceiving portion 408. The HSA shipping tray receiving portion 408 maybe configured to receive a HSA shipping tray 102 such as thatillustrated in FIGS. 1 and 2. Likewise, the VCM shipping tray receivingportion 406 of the assembly station 400 may be configured to receive aVCM shipping tray (not shown) that may be similar in construction to theHSA shipping tray 102 shown in FIGS. 1 and 2, but configured to receivea plurality of VCMs. Alternatively, HSAs and/or VCMs may be delivered tothe assembly station 400 by other means. For example, the HSAs mayarrive at the assembly station 400 by means of the disk drive assemblyconveyor in a single or in multiple configurations and orientations. TheHSAs and/or VCMs might also be manually delivered to the assemblystation 400.

The assembly station 400 may further include (but need not so include)an HDA nest 412 to which disk drive bases, such as disk drive base 302,conveyed to the assembly station 400 may be coupled to complete one ormore assembly steps. The assembly station 400 may also include a robotictool 402 for assembling a portion of a disk drive. As best shown in FIG.5, the assembly station 400 may also include a VCM air merge nest 502that is configured to merge together an HSA and a VCM, such that theresulting assembly is suitable for coupling to the disk drive base.

The robotic tool 402 may, according to embodiments of the presentinvention, include an end effector 404 that is controllable and movableby the robotic tool 402. The body of the robotic tool 402 may bearticulated (by servo motors for example) to selectively move the endeffector 404 to, from and in between the VCM shipping tray receivingportion 406, the HSA shipping tray receiving portion 408, the air mergenest 502, the conveyor 410 and the HDA nest 412. The end effector 404 ispreferably configured to selectively pick and place various disk driveworkpieces between these locations within the disk drive assemblystation 400.

A down-facing camera 414 may also be coupled to the end effector 404.The down-facing camera 414 may be configured to provide visualpositional cues to a controller (not shown) of the robotic tool 402. Thedown-facing camera 414 may include, for example, a high resolution blackand white progressive scan CCD (Charge Coupled Device) video camera suchas the XC-HR70 available from Sony Corporation. The XC-HR70 features a⅓″ type IT progressive scan CCD and has a horizontal resolution of 1034pixels and a vertical resolution of 779 pixels, enabling it to captureimages at 29 f/s. Other video cameras may be used, and the opticsthereof adapted to the specific requirements of the implementation athand. Indeed, as would be clear to one skilled in the art, any means forcapturing a preferably high-resolution image may be used. As also shownin FIG. 4, a telecentric lens 416 may be coupled to the down-facingcamera 414 and a light source 418, such as a Diffuse On Access Light(DOAL) for example, may be coupled to the lens 416.

In addition, it should be understood by those skilled in the art thatany suitable controller or processor may implement the functionalitydescribed herein. Indeed, the controller may comprise a plurality ofmicroprocessors and controllers working to perform the desiredfunctions. In one embodiment, the controller may comprise amicroprocessor executing instructions, the instructions being operableto cause the microprocessor to perform the steps described herein. Theinstructions may be stored in any computer-readable medium. In oneembodiment, they may be stored on a non-volatile semiconductor memoryexternal to the microprocessor, or integrated with the microprocessor.In another embodiment, the instructions may be stored on a disk and readinto a volatile semiconductor memory before execution by themicroprocessor. In yet another embodiment, the controller comprisessuitable logic circuitry, such as state machine circuitry.

FIG. 6 shows a HSA 106 coupled to the end effector 404 of the robotictool of FIG. 4. Note that FIG. 6 does not show a VCM coupled to the HSA106. As shown therein, the end effector 404 may include a first portion602 and a second portion 604. The first portion 602 may be configured toengage the actuator assembly, and the second portion 604 may beconfigured to engage the FCC 110. According to an embodiment of thepresent invention, the second portion 604 of the end effector 404 may beconfigured to move relative to the first portion 602.

According to an embodiment of the present invention, the controller maybe configured to control the end effector 404, and may be operable tocause the end effector 404 to move to the HSA shipping tray receivingportion 408 and to engage and pick up a HSA 106 from a HSA shipping tray102 (shown in FIGS. 1 and 2 only). In other embodiments, of course, theend effector 404 may pick up a HSA 106 in any of a number of locationsor orientations according to information gathered by the down-facingcamera 414. To pick up the HSA 106, the robotic tool 402 may becontrolled to position the down-facing camera 414 over the HSA shippingtray 102 and to record an image of the HSA 106. The end effector 404 maythen be controlled to move over the imaged HSA 106, and a barcode reader606 or other machine vision device coupled to the end effector 404 mayread a barcode or other machine-readable indicia (if such is present) onthe HSA.

The HSA 106, as detailed above, may be disposed within the shipping tray102 in a first configuration. This first configuration may be that shownin FIG. 2, in which the flex circuit is generally disposed a distance204 away from the tail stack 202 of the HSA 106. Other configurations ofthe HSA are, of course, possible. Herein, the term “actuator assembly”includes at least the assembly of the actuator arms and the actuatorbody, whether or not these form a unitary piece. The configuration inwhich the end effector 404 engages the HSA 106 may also be characterizedas the shipping configuration of the HSA 106.

The end effector 404 is typically moved to a position verticallyadjacent the HSA 106. Vacuum may then be turned on to couple the FCC 110to the second portion 604 of the end effector 404, through a suction cupfitted to the second portion 604, for example. The first portion 602 mayengage and couple the HSA 106 through engagement of, for example, two ormore fingers of a pneumatic air gripper coupled to the first portion 602of the end effector 404. Suitable air grippers may be obtained from, forexample, SMC Corporation of America of Indianapolis, Ind. A three fingerpneumatic air gripper from SMC is the MHR3-10R model. The MHR3-10R modeloperates by moving the tooling fingers apart by pneumatic pressure.However, air grippers are also available in rotary driven, two, threeand four finger parallel styles that are effective to reliably grip andcenter workpieces (such as HSAs, for example). Other available modelsinclude wide opening parallel models; angular models having a speedadjustment built in; models having a toggle to give reliable grippingsupport; models suitable for clean room or low-contaminationenvironments that are equipped with a protective boot, etc. Other typesof grippers, actuated by hydraulic, electrical or piezo-electrical means(for example), may be used as well.

The pneumatic air gripper coupled to the first portion 602 maymechanically grip a pivot assembly (or one or more of the constituentsub-components thereof) of the HSA 106 at, for example, a correspondingengagement feature defined in or about the shaft of the HSA 106. In oneembodiment, for example, first and second fingers of first portion 602may be moved in order to mechanically grip the pivot assembly of theactuator assembly. A number of different pneumatic air grippers andcorresponding features defined within the pivot assembly of the HSA aredisclosed in commonly assigned and co-pending U.S. patent applicationSer. No. 11/257,368 entitled “Tooling Mandrel For Assembling A DiskDrive And Method Of Using The Same” filed on Oct. 24, 2005, thedisclosure of which is incorporated herein by reference. According toone embodiment of the present invention, the second portion 604 of theend effector may engage and couple to the FCC 110 through suction,although other mechanisms for coupling the FCC 110 to the second portion604 may readily be implemented. Indeed, the end effector 404 maycomprise any of a number of different designs used to manipulateworkpieces. In one embodiment, the end effector comprises a single,articulable grasping mechanism. Preferably, this grasping mechanism iscapable of grasping at least two objects (e.g., an actuator assembly andFCC) and manipulating these objects independently. In anotherembodiment, the end effector may comprise at least two vacuumconnections that are independently movable. In the preferred embodiment,the end effector comprises first and second portions that are movablerelative to one another.

The end effector may then be controlled to rise vertically away from theHSA shipping tray 102 with the entire HSA 106 gripped in the firstconfiguration (e.g., the same configuration in which the HSA 106 wasdisposed in the shipping tray 102). According to an embodiment of thepresent invention, now that the HSA 106 is engaged and coupled to thefirst portion 602, the FCC 110 is coupled to the second portion 604 ofthe end effector 404 and the end effector has cleared the shipping tray102, the second portion 604 may be moved relative to the first portion602 of the end effector 404, so as to articulate the HSA 106 into asecond configuration that is different than the first configuration.According to an embodiment of the present invention, this secondconfiguration may be one in which the HSA 106 is in a configuration thatis suitable for loading into a disk drive base.

Reference is now made to FIGS. 7A and 7B. FIG. 7A shows the HSA 106coupled to the end effector 404 and disposed in the first (e.g.,shipping) configuration, whereas FIG. 7B shows the HSA 106 coupled tothe end effector 404 and disposed in the second (e.g., loading)configuration. To articulate the HSA 106 from the first configurationshown in FIG. 7A to the second configuration shown in FIG. 7B, thesecond portion 604 of the end effector 404 may be moved relative to thefirst portion 602 thereof. Thus, in one embodiment, the end effector 404itself may be articulated to change the configuration of the HSA 106. Ascollectively shown in FIGS. 7A and 7B, moving the second portion 604relative to the first portion 602, for example in the direction of arrow704 in FIG. 7A, articulates the HSA 106 to a configuration that issuitable for coupling the HSA 106 to the disk drive base 302. Inparticular, moving the second portion 604 of the end effector 404relative to the first portion 602, may move the FCC 110 closer to theactuator arms and actuator body of the actuator assembly of the HSA 106.In so doing, the FCC 110 may be moved closer to the actuator assembly ofthe HSA 106 in the second configuration of FIG. 7B than in the firstconfiguration shown in FIG. 7A. That is, as shown in FIG. 7B, the flexcircuit 108 may be brought into close proximity with the tail stack ofthe HSA 106 and into close proximity with other structures thereof.However, as the movement of the second portion 604 relative to the firstportion 602 is precisely controlled, the flex circuit is less apt tocome into contact with any structures of the actuator assembly of theHSA 106.

As a result of the movement of the second portion 604 relative to thefirst portion 602, the HSA 106 may be placed in a configuration thatenables it to be placed into the base 302 of the disk drive beingassembled. To place the HSA 106, the controller of the robotic tool mayfirst control the end effector 404 to move to a position above andaligned with the HDA nest 412, where the disk drive base 302 haspreviously been moved. The controller may then cause the end effector404 to place the HSA 106 into the base 302 while the base is coupled tothe HDA nest 412. In one embodiment, the controller uses feedback fromthe down-facing camera 414 in order to manipulate the end effector 404and thereby the HSA 106. In another embodiment, the base 302 may bemoved to a position under the end effector 404, instead of moving theend effector 404 to a position over the base 302. The shipping comb 206interdigitated between the suspensions of the HSA 106 may then beremoved, thereby allowing a lift tab or tabs of the HSA 106 to come intocontact with a ramp coupled to the base 302.

As described relative to FIG. 5, the robotic tool may include an airmerge nest 502 that is configured to enable the HSA 106 to be mergedwith opposing magnets of a VCM, shown at reference number 702 in FIG.7B. According to an embodiment of the present invention, prior to movingthe second portion 604 relative to the first portion 602, and prior toplacing the HSA 106 into the base 302, the end effector 404 may becontrolled to place the HSA 106 into the air merge nest 502. Indeed, therobotic tool may be controlled to articulate the end effector 404 suchthat the coupled HSA 106 is in a third configuration, to release theactuator assembly into the air merge nest 502, and to shut off thesuction such that the FCC 110 is no longer coupled to the second portion604 of the end effector 404. The robotic tool may then control the endeffector 404 to move away from the air merge nest 502.

The end effector 404 may then be moved to a position above the VCMsloaded in a VCM shipping tray disposed within the VCM shipping trayreceiving portion 406 of the assembly station 400. The down-facingcamera 414 may be used to record an image of a selected VCM within theVCM shipping tray. The end effector 404 may then be controlled to pickup the imaged VCM. The robotic tool may also move the end effector 404to a screw feeder (not shown) to pick up a screw therefrom. Whileretaining the screw, the end effector 404 may be controlled to place thepicked up VCM within the air merge nest 502, where the HSA 106 and theVCM are to be air merged. The end effector 404 may be controlled tocarry out other functions, including, for example, picking and placing apivot screw with which the HSA 106 is to be coupled to the base 302 andscanning a barcode or other machine-readable indicia on the HSA 106 ordisk drive base 302.

The air merge nest 502 functions in a manner well known to those ofskill in the art. Once the VCM and HSA are loaded therein, the VCM maybe rotated such that the HSA fantail may slide between the two opposingmagnets of the VCM. The air merge nest 502 may be provided with apneumatic rotary device to rotate the VCM. The air merge nest 502 maythen be controlled to cause the fantail to slide into the space betweenthe two opposing VCM magnets. The HSA 106 may then be moved by atwo-position air slide, and the VCM may be rotated back to a loadposition. In one embodiment, the HSA 106 may be in the firstconfiguration during the air merge operation, while in other embodimentsthe HSA 106 may be in the second or other configurations during the airmerge operation.

After air merge, the combined HSA and VCM assembly may be picked fromthe air merge nest 502 by the end effector 404. The down-facing camera414 may then be controlled to move over the HDA nest 412. An image ofthe disk drive base 302 may then be taken and recorded by the camera414, so that the correct placement of the combined HSA and VCM assemblymay be determined. The retained screw may then be placed into anup-facing screwdriver (not shown) so that the retained screw may bedriven through the base and into the pivot assembly of the HSA 106. Thecombined HSA and VCM assembly may then be placed into the base 302. Thepneumatic air gripper may then be controlled to relax its grip on thepivot assembly of the HSA 106, and the suction holding the FCC 110 maybe turned off. The end effector 404 may then be controlled to rise andclear the HDA nest 412 and the HDA captive therein.

1. A robotic tool for assembling a portion of a disk drive, the diskdrive including a base and a head stack assembly, the head stackassembly including an actuator assembly, a flex circuit coupled to theactuator assembly and a flex circuit connector coupled to the flexcircuit, the robotic tool comprising: a movable end effector including afirst portion and a second portion that is movable relative to the firstportion, the first portion being configured to engage the actuatorassembly and the second portion being configured to engage the flexcircuit connector; and a controller configured to control the movableend effector, the controller operable to cause the end effector to: pickup the head stack assembly in a first configuration; move the secondportion of the end effector relative to the first portion thereof so asto articulate the head stack assembly into a second configuration thatis different than the first configuration; and place the head stackassembly into the base.
 2. The robotic tool of claim 1, wherein theactuator assembly includes a pivot assembly and wherein the firstportion includes fingers configured to grip the pivot assembly andwherein the second portion is configured to apply suction to the flexcircuit connector.
 3. The robotic tool of claim 1, further comprising anair merge nest configured to enable the head stack assembly to be mergedwith magnets of a voice coil motor.
 4. The robotic tool of claim 3,wherein the controller is further operable to cause the movable endeffector to merge the head stack assembly with the magnets of the voicecoil motor in the air merge nest before the head stack assembly isplaced into the base.